from qrcode import constants

EXP_TABLE = list(range(256))

LOG_TABLE = list(range(256))

for i in range(8):
    EXP_TABLE[i] = 1 << i

for i in range(8, 256):
    EXP_TABLE[i] = (
        EXP_TABLE[i - 4] ^ EXP_TABLE[i - 5] ^ EXP_TABLE[i - 6] ^
        EXP_TABLE[i - 8])

for i in range(255):
    LOG_TABLE[EXP_TABLE[i]] = i

RS_BLOCK_OFFSET = {
    constants.ERROR_CORRECT_L: 0,
    constants.ERROR_CORRECT_M: 1,
    constants.ERROR_CORRECT_Q: 2,
    constants.ERROR_CORRECT_H: 3,
}

RS_BLOCK_TABLE = (

    # L
    # M
    # Q
    # H

    # 1
    (1, 26, 19),
    (1, 26, 16),
    (1, 26, 13),
    (1, 26, 9),

    # 2
    (1, 44, 34),
    (1, 44, 28),
    (1, 44, 22),
    (1, 44, 16),

    # 3
    (1, 70, 55),
    (1, 70, 44),
    (2, 35, 17),
    (2, 35, 13),

    # 4
    (1, 100, 80),
    (2, 50, 32),
    (2, 50, 24),
    (4, 25, 9),

    # 5
    (1, 134, 108),
    (2, 67, 43),
    (2, 33, 15, 2, 34, 16),
    (2, 33, 11, 2, 34, 12),

    # 6
    (2, 86, 68),
    (4, 43, 27),
    (4, 43, 19),
    (4, 43, 15),

    # 7
    (2, 98, 78),
    (4, 49, 31),
    (2, 32, 14, 4, 33, 15),
    (4, 39, 13, 1, 40, 14),

    # 8
    (2, 121, 97),
    (2, 60, 38, 2, 61, 39),
    (4, 40, 18, 2, 41, 19),
    (4, 40, 14, 2, 41, 15),

    # 9
    (2, 146, 116),
    (3, 58, 36, 2, 59, 37),
    (4, 36, 16, 4, 37, 17),
    (4, 36, 12, 4, 37, 13),

    # 10
    (2, 86, 68, 2, 87, 69),
    (4, 69, 43, 1, 70, 44),
    (6, 43, 19, 2, 44, 20),
    (6, 43, 15, 2, 44, 16),

    # 11
    (4, 101, 81),
    (1, 80, 50, 4, 81, 51),
    (4, 50, 22, 4, 51, 23),
    (3, 36, 12, 8, 37, 13),

    # 12
    (2, 116, 92, 2, 117, 93),
    (6, 58, 36, 2, 59, 37),
    (4, 46, 20, 6, 47, 21),
    (7, 42, 14, 4, 43, 15),

    # 13
    (4, 133, 107),
    (8, 59, 37, 1, 60, 38),
    (8, 44, 20, 4, 45, 21),
    (12, 33, 11, 4, 34, 12),

    # 14
    (3, 145, 115, 1, 146, 116),
    (4, 64, 40, 5, 65, 41),
    (11, 36, 16, 5, 37, 17),
    (11, 36, 12, 5, 37, 13),

    # 15
    (5, 109, 87, 1, 110, 88),
    (5, 65, 41, 5, 66, 42),
    (5, 54, 24, 7, 55, 25),
    (11, 36, 12, 7, 37, 13),

    # 16
    (5, 122, 98, 1, 123, 99),
    (7, 73, 45, 3, 74, 46),
    (15, 43, 19, 2, 44, 20),
    (3, 45, 15, 13, 46, 16),

    # 17
    (1, 135, 107, 5, 136, 108),
    (10, 74, 46, 1, 75, 47),
    (1, 50, 22, 15, 51, 23),
    (2, 42, 14, 17, 43, 15),

    # 18
    (5, 150, 120, 1, 151, 121),
    (9, 69, 43, 4, 70, 44),
    (17, 50, 22, 1, 51, 23),
    (2, 42, 14, 19, 43, 15),

    # 19
    (3, 141, 113, 4, 142, 114),
    (3, 70, 44, 11, 71, 45),
    (17, 47, 21, 4, 48, 22),
    (9, 39, 13, 16, 40, 14),

    # 20
    (3, 135, 107, 5, 136, 108),
    (3, 67, 41, 13, 68, 42),
    (15, 54, 24, 5, 55, 25),
    (15, 43, 15, 10, 44, 16),

    # 21
    (4, 144, 116, 4, 145, 117),
    (17, 68, 42),
    (17, 50, 22, 6, 51, 23),
    (19, 46, 16, 6, 47, 17),

    # 22
    (2, 139, 111, 7, 140, 112),
    (17, 74, 46),
    (7, 54, 24, 16, 55, 25),
    (34, 37, 13),

    # 23
    (4, 151, 121, 5, 152, 122),
    (4, 75, 47, 14, 76, 48),
    (11, 54, 24, 14, 55, 25),
    (16, 45, 15, 14, 46, 16),

    # 24
    (6, 147, 117, 4, 148, 118),
    (6, 73, 45, 14, 74, 46),
    (11, 54, 24, 16, 55, 25),
    (30, 46, 16, 2, 47, 17),

    # 25
    (8, 132, 106, 4, 133, 107),
    (8, 75, 47, 13, 76, 48),
    (7, 54, 24, 22, 55, 25),
    (22, 45, 15, 13, 46, 16),

    # 26
    (10, 142, 114, 2, 143, 115),
    (19, 74, 46, 4, 75, 47),
    (28, 50, 22, 6, 51, 23),
    (33, 46, 16, 4, 47, 17),

    # 27
    (8, 152, 122, 4, 153, 123),
    (22, 73, 45, 3, 74, 46),
    (8, 53, 23, 26, 54, 24),
    (12, 45, 15, 28, 46, 16),

    # 28
    (3, 147, 117, 10, 148, 118),
    (3, 73, 45, 23, 74, 46),
    (4, 54, 24, 31, 55, 25),
    (11, 45, 15, 31, 46, 16),

    # 29
    (7, 146, 116, 7, 147, 117),
    (21, 73, 45, 7, 74, 46),
    (1, 53, 23, 37, 54, 24),
    (19, 45, 15, 26, 46, 16),

    # 30
    (5, 145, 115, 10, 146, 116),
    (19, 75, 47, 10, 76, 48),
    (15, 54, 24, 25, 55, 25),
    (23, 45, 15, 25, 46, 16),

    # 31
    (13, 145, 115, 3, 146, 116),
    (2, 74, 46, 29, 75, 47),
    (42, 54, 24, 1, 55, 25),
    (23, 45, 15, 28, 46, 16),

    # 32
    (17, 145, 115),
    (10, 74, 46, 23, 75, 47),
    (10, 54, 24, 35, 55, 25),
    (19, 45, 15, 35, 46, 16),

    # 33
    (17, 145, 115, 1, 146, 116),
    (14, 74, 46, 21, 75, 47),
    (29, 54, 24, 19, 55, 25),
    (11, 45, 15, 46, 46, 16),

    # 34
    (13, 145, 115, 6, 146, 116),
    (14, 74, 46, 23, 75, 47),
    (44, 54, 24, 7, 55, 25),
    (59, 46, 16, 1, 47, 17),

    # 35
    (12, 151, 121, 7, 152, 122),
    (12, 75, 47, 26, 76, 48),
    (39, 54, 24, 14, 55, 25),
    (22, 45, 15, 41, 46, 16),

    # 36
    (6, 151, 121, 14, 152, 122),
    (6, 75, 47, 34, 76, 48),
    (46, 54, 24, 10, 55, 25),
    (2, 45, 15, 64, 46, 16),

    # 37
    (17, 152, 122, 4, 153, 123),
    (29, 74, 46, 14, 75, 47),
    (49, 54, 24, 10, 55, 25),
    (24, 45, 15, 46, 46, 16),

    # 38
    (4, 152, 122, 18, 153, 123),
    (13, 74, 46, 32, 75, 47),
    (48, 54, 24, 14, 55, 25),
    (42, 45, 15, 32, 46, 16),

    # 39
    (20, 147, 117, 4, 148, 118),
    (40, 75, 47, 7, 76, 48),
    (43, 54, 24, 22, 55, 25),
    (10, 45, 15, 67, 46, 16),

    # 40
    (19, 148, 118, 6, 149, 119),
    (18, 75, 47, 31, 76, 48),
    (34, 54, 24, 34, 55, 25),
    (20, 45, 15, 61, 46, 16)

)


def glog(n):
    if n < 1:  # pragma: no cover
        raise ValueError(f"glog({n})")
    return LOG_TABLE[n]


def gexp(n):
    return EXP_TABLE[n % 255]


class Polynomial:

    def __init__(self, num, shift):
        if not num:  # pragma: no cover
            raise Exception(f"{len(num)}/{shift}")

        for offset in range(len(num)):
            if num[offset] != 0:
                break
        else:
            offset += 1

        self.num = num[offset:] + [0] * shift

    def __getitem__(self, index):
        return self.num[index]

    def __iter__(self):
        return iter(self.num)

    def __len__(self):
        return len(self.num)

    def __mul__(self, other):
        num = [0] * (len(self) + len(other) - 1)

        for i, item in enumerate(self):
            for j, other_item in enumerate(other):
                num[i + j] ^= gexp(glog(item) + glog(other_item))

        return Polynomial(num, 0)

    def __mod__(self, other):
        difference = len(self) - len(other)
        if difference < 0:
            return self

        ratio = glog(self[0]) - glog(other[0])

        num = [
            item ^ gexp(glog(other_item) + ratio)
            for item, other_item in zip(self, other)]
        if difference:
            num.extend(self[-difference:])

        # recursive call
        return Polynomial(num, 0) % other


class RSBlock:

    def __init__(self, total_count, data_count):
        self.total_count = total_count
        self.data_count = data_count


def rs_blocks(version, error_correction):
    if error_correction not in RS_BLOCK_OFFSET:  # pragma: no cover
        raise Exception(
            "bad rs block @ version: %s / error_correction: %s" %
            (version, error_correction))
    offset = RS_BLOCK_OFFSET[error_correction]
    rs_block = RS_BLOCK_TABLE[(version - 1) * 4 + offset]

    blocks = []

    for i in range(0, len(rs_block), 3):
        count, total_count, data_count = rs_block[i:i + 3]
        for _ in range(count):
            blocks.append(RSBlock(total_count, data_count))

    return blocks
